$ { \left[\begin{array}{rr}{2} & {1} \\ {3} & {-1}\end{array}\right]+\left[\begin{array}{rr}{-2} & {0} \\ {0} & {3}\end{array}\right] = {?} } $
Explanation: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{2}+{-2} & {1}+{0} \\ {3}+{0} & {-1}+{3}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{0} & {1} \\ {3} & {2}\end{array}\right]}$